Chronic reactivation of experimental rabies in a cat was apparent from worsening sequelae after a period of quiescence. The deteriorating clinical condition was accompanied by marked increase in antibody titers in cerebrospinal fluid and in serum. Electron microscopy and light microscopy of lesions obtained at necropsy revealed lesions resembling those reported in animals and in man by Russian workers. Early appearing and persistent rabies antibody-reactive antigen has been found in the skin of a large proportion of rabies-infected animals. The technique is successful when applied to punch biopsy specimens obtained during life. Mice kept in a hyperthermic ambience are more resistant to rabies. The effect is largely on the host rather than on the virus because in many animals onset of illness is merely delayed rather than prevented.